Update protobuf-java to 2.5.0 in upstart.conf.erb

New versions of XtreemFS include protobuf-java-2.5.0.jar instead 2.3.0.
Update upstart template with new version.
Merge pull request #1 from juanluisrp/protobuf-version

Update protobuf-java to 2.5.0 in upstart.conf.erb